Screening or draining apparatus



Oct. 27, 1959 A. WEHNER SCREENING OR IDRAINING APPARATUS Filed Dec. 28, 1956' F/GT 4 INVENIOP QZ/at UM surrounding the belt. with the sludge, accommodates a comparatively large United States Patent SCREENING R DRAINING APPARATUS Albert Wehner, Heme, Westphalia, Germany Application December 28, 1956, Serial No. 631,188

Claims priority, application Belgium December 30, 1955 6 Claims. or. 210- 388) The invention relates to screening or draining apparatus, the screening or permeable area of which is formed by an endless moving belt, and more particularly to a particularly advantageous construction of such a screening belt, in which the permeable surface of the belt, during its movement, has a vibratory motion imparted thereto transversely of the screening area, such vibratory motion being produced by the fact that camlike profiles on cam strips composed of resilient material and disposed about the screening belt move over projections which are suitably spaced one from another and form a corrugated guide surface and which are fixed or move in the opposite direction to the cams.

The object of the invention is to provide an improved screening and draining apparatus of this character by means of which the apparatus is enabled with a high degree of elficiency to drain sludges containing solid materials in finely divided form.

It is well known that the difiiculties of draining materials of this nature, such as coal sludge, ceramic slurries, paper pulp and the like, increase as the size of the solid particles decreases, so that an adequate draining or filtering with the requisite degree of etnciency is no longer possible with draining means of the usual kind.

The output of the apparatus-shaking screens provided with fine-mesh wire cloth, suction filters, centrifugal apparatus or filter pressesheretofore available for the filtering of these sludges is much too small for largescale industrial use.

According to the invention the screening belt is divided by means of transverse partitions of porous resilient material into a plurality of individual troughs which are closed ofi laterally by the side walls of a casing Each trough, when being charged quantity of the sludge and the filtrate, upon advance of the belt, flows off in a rapidly progressive fashion, 'assisted by the vibratory motion of the belt, through the permeable bottoms of the troughs. The solid material deposited on the bottoms of the troughs is utilized as a fine filtering layer and a degree of drainage is achieved which can be predetermined by the length of the belt set into vibration and its rate of travel. In order further to assist the drainage, the side walls of the casing in the regions in which they form the lateral closure means for the troughs may be made permeable.

According to a particularly advantageous embodiment of the invention, the draining operation is further improved by the fact that, after most of the liquid has been discharged, the resilient and permeable partitions providing the individual troughs are, by means of fixed elements past which they move, deflected in a direction opposite to the direction of movement of the material and pressed against the bottoms of the troughs with simultaneous compression of the already extensively drained material located on the bottoms of the troughs.

This may, for example, be eifected by rollers mounted in the casing. However, according to a particularly walls 2, 2' of the casing surrounding the belt, which walls 'fl 2,910,185 1C6 Patented Oct. 27, 195

advantageous embodiment of the invention, it may be effected by making the wall of the casing above the belt in the regions in question gradually extend downwards towards the belt.

The belt may be guided horizontally in its effective region. It has been found better, however, to guide the belt in this region arcuately over a drum. In this case the casing, at least in the region of the discharge side,

preferably surrounds the drum in gradually decreasing spacing from the drum so that as the belt moves past the casing wall in this narrowed portion the partitions are automatically gradually deflected and then automatically assume an upright position under their own elasticity. By reason of the vibratory motion impressed continuously on the belt, there occurs during the total operation a progressive formation anew of gaps between the individual components of the solid material, resulting in .a good discharge of the filtrate.

The draining operation, as is usual in the filtering art, may be improved by the use of a reduced pressure or, with greater advantage, by an alternating positive pressure and negative pressure. The extensively drained solid materials separated may easily be subjected to the action of dry air.

Two embodiments of drainage apparatus according to the invention are illustrated in the accompanying drawings, in which Figure 1 is a longitudinal sectional view of one embodiment showing the effective region of the screening belt horizontally disposed,

Figure 2 is a transverse sectional view of the embodiment shown in Figure 1, and

Figures 3 and 4 are views similar tothose of Figures 1 and 2 respectively showing the second embodiment wherein the belt in the efiective drainage region is passed about a drum.

According to Figure l the belt comprises an endless band of permeable material sub-divided in the transverse direction by means of permeable and elastic or resilient partitions 1 which are provided with layers 1' of porous material, so that consecutive troughs are formed, the bottoms of which are lined with a porous layer of foam i'ullzber or other filtering material, if desired with wire a no.

The compartments formed are completed by the side closely adjoin the moved parts of the belt, and if desired, by-the upper wall 3 illustrated, so that moving compartments are formed which are completely closed in and k have permeable bottoms and permeable transverse walls.

The side portions of the casing forming the lateral closures for these compartments may also be made permeable, for example perforated. 1 The belt, which possesses marginal strips 5 of corrugated form, passes over reversing drums 4, 4' having a profile corresponding to the form of the marginal strips.

;The vibratory motion is imparted to the screening belt by means of a short endless belt 7 which is mounted within the space surrounded by the conveying belt or band and passes about reversing drums 6, 6' and to which are secured rollers 8 spaced to correspond to the corrugated form of the marginal strips 5. The endless belt 7 carrying the rollers 8 preferably comprises two lateral strips connected together by the rollers 8. With the object of producing vibrations of particularly high frequency the belt 7 may be driven in known manner in a direction opposite to that of the actual screening belt, although if desired it may be driven in the same direction with a movement relative to that of the screening belt.

Rollers 9, 9 are provided in the supporting structure in the regions below the reversing points of the screening belt these rollers may, if desired, be furnished with a soft facing and, as shown in the drawings, deflect the partitions as they pass the rollers in a direction opposite to the direction of movement of the belt and press them against the contents of the compartments. In this way there is obtained on the discharge side of the belt an additional drainage of liquid and ahead of the charging point a removal of moisture from the belt, which is cleaned by means of a spraying device indicated diagrammatically at 10 and disposed ahead of roller 9.

Discharge of the drained material, which falls away from the bottoms of the troughs after the reversal, is efiected in accordance with the embodiment illustrated by means of a transverse belt 11, whilst the water or other filtrate is discharged by a gully indicated diagrammatically at 12 and located transversely of the direction of movement of the drainage belt in the space surrounded thereby. The complete belt structure described may be so designed as to be capable of being rocked in height about one or the other point of reversal, so that it is possible to dispose the belt in an inclined position and thus, if desired, to exercise control over the drainage effect. In addition or alternatively the belt may be rocked laterally.

The embodiment of the invention illustrated in Figures 3 and 4 differs in substance from that according to Figures 1 and 2 solely in that the belt, which otherwise is constructed in similar fashion and also moves in a surrounding casing is not extended longitudinally in its effective region but is passed about a drum 13 of comparatively large diameter-of the order of 0.5 to 2 metres. The belt, which is also furnished with the corrugated marginal strips 5', is driven by a correspondingly profiled drum 4". The drum 13 is driven independently of the belt in the direction opposite to the direction of travel of the belt and carries on its periphery rollers 8 which, in the manner already described above in conjunction with Figures 1 and 2, co-operate with the marginal strips 5' to produce the vibratory motion.

The downwardly extending upper wall 3' gradually approaches the belt on the discharge side thereof and causes a gradual deflection of the partitions 1" in a direction opposite to the direction of travel of the belt and thus an additional drainage of the material contained in the chambers owing to a compression thereof, i.e., a reduction in the volume of the chambers. Ahead of the feeding point of the material it is possible by the resiliently mounted pressure roller 9 to squeeze out the water from the belt, which has previously been cleaned by the spraying device 10', in a similar way to that shown in Figure 1.

In both embodiments shown it is possible, with a view to obtaining an even better drainage efiect, to produce, by connection of the space within the belt to a vacuum source, a reduced pressure within such space or, if desired, a pulsating positive and negative pressure, whereby the pores between the solid components are alternately opened.

The invention is not limited to use for drainage purposes and the principle of the new bolt may be employed for the carrying out of other operations, for example pure screening and sifting operations, in which case the pervious facing of the belt may then consist, for example, of a wire cloth, which is applied in corrugated form and is secured in the region of the troughs in the corrugations. A covering of this nature itself operates under the action of the vibratory motion impressed on the surface of the belt, and thus additionally assists in obtaining the screening or sitting effect.

I claim:

1. A de-watering apparatus comprising a housing with side walls, an endless permeable belt continuously moving between and'along said side walls in said housing, rotating means to guide and support said belt within said housing at the points of reversal of said belt, means in said housing for subjecting said belt to a vibratory motion transversely with respect to the running direction of said belt, transverse partitions of porous resilient material projecting from said belt and dividing the same into trough-like compartments for which said belt forms porous bottoms, said side walls of said housing forming lateral boundaries for said compartments, and means in said housing at at least one of said rotating means for deflecting said partitions against said bottoms of said compartments. 7

2. A de-watering apparatus according to claim I, wherein said side walls of said housing are at least partially permeable along said belt at the zones of said compartments.

3. A de-watering apparatus according to claim 1, wherein the surfaces of said porous bottoms facing toward the interior of said compartments are made of spongelike water-absorbing material.

4. A de-watering apparatus according to claim 3, wherein the surfaces of said transverse partitions facing toward the interior of said compartments are made of sponge-like Water-absorbing material.

5. A de-watering apparatus comprising a housing with side walls, an endless permeable belt continuously moving between and along said side walls in said housing, a rotating roller to guide and drive said belt within said housing, a rotatable drum larger than said roller in said housing for supporting said belt and subjecting it to a vibratory motion transversely with respect to the running direction of said belt, transverse partitions of porous resilient material projecting from said belt and dividing the same into trough-like compartments for which said belt forms porous bottoms, said side walls of said housing forming lateral boundaries for said compartments, means in said housing at said driun for deflecting said partitions against said bottoms of said compartments.

6. A de-watering apparatus according to claim 5, wherein said deflecting means is formed by a portion of said housing at the discharge side of said belt, said housing portion gradually approaching said belt at said rotating drum and then receding therefrom to cause said partitions to be gradually bent towards said bottoms and then permitting them to return to their original erect position on said belt.

References Cited in the file of this patent UNITED STATES PATENTS 1,958,279 Morgan May 8, 1934 2,104,785 Akeyson Ian. 11, 1938 2,688,406 Holland Sept. 7, 1954 

